This invention provides hardenable compositions useful as construction media for a wide range of applications. Particular utility is found in the dental and medical arts where such compositions are highly suitable for the formation and construction of artificial teeth and for other dental and prosthetic uses. More particularly, the invention relates to polymeric compositions comprising crosslinked polymers, monomers, and crosslinking agents for said monomers, and optionally uncrosslinked polymers which form precursor blends. These precursor blends are capable of being formed or molded and caused to polymerize to provide articles possessing superior physical and physiochemical properties.
Artificial teeth should exhibit certain physical and physiochemical characteristics to be suitable for use. They should be hard and resistant to chipping, durable, and stable to solvents, water, and heat. In addition, they should be of an aesthetically acceptable color, i.e., close to that of natural teeth, or be amenable to artificial coloration. The teeth should not cause excessive wear to opposing natural or artificial teeth, should not wear out of occlusion, and should be capable of being bonded firmly to supportive structures. They should also be amenable to ordinary means of physical shaping, grinding, and polishing, so as to minimize production costs.
Various metals and ceramics have been traditionally used for the formation of artificial teeth and other dental appliances. These, however, possess certain inherent deficiencies which lessen their desirability in dental applications. Thus, the metallic color of gold, amalgam, and other metallic species serves as an aesthetic detraction to the wearer of appliances made therefrom. In addition, the high cost of most noble metals from which many such appliances are commonly made leads to a cost consideration whenever their use is contemplated. Ceramic materials, another common alternative, are often difficult to form into acceptable shapes, and may tend to evidence abrasive and aesthetically unpleasant subsurfaces upon the physical wearing-away of surface layers. Such materials are also difficult to polish satisfactorily. These reasons together with factors related to cost, to consumer preference, to the technical skills of dental practitioners, and to convenience have motivated a search for alternative compositions suitable for the construction of dental appliances, especially artificial teeth.
Of the presently available organic compositions used for the construction of artificial teeth, most are composed of acrylics, often crosslinked by polyfunctional moieties. While such compositions are now commonly in use, they nonetheless possess certain drawbacks. In general, currently available acrylic compositions are only poorly resistant to wearing and grinding and may stain easily. Moreover, their mechanical workability is poor and they tend to melt and smear when ground. Their resistance to heat and to solvents is often poor, and in some cases, they are hydrolytically unstable.
Accordingly, it is a principal object of this invention to provide compositions which are useful in the construction of artificial teeth and other dental appliances, which compositions lead to products having improved workability and superior physical and aesthetic characteristics.